function getXMLHttpObject() {
	var xmlHTTP = false;
	var xhrNames = [ "MSXML2.XMLHTTP.6.0", "MSXML2.XMLHTTP.3.0",
			"MSXML2.XMLHTTP", "Microsoft.XMLHTTP" ];
	for ( var i = 0; i < xhrNames.length; i++) {
		try {
			xmlHTTP = new ActiveXObject(xhrNames[i]);
			break;
		} catch (e) {
		}
	}
	if (!xmlHTTP && typeof XMLHttpRequest != "undefined") {
		xmlHTTP = new XMLHttpRequest();
	}
	return xmlHTTP;
}
function makerequest(username, objID) {
	var obj = document.getElementById(objID);
	var xmlHTTP = getXMLHttpObject();
	xmlHTTP.open("GET", "KiemTraTenDangNhapDaTonTai.do?username=" + username);
	xmlHTTP.onreadystatechange = function() {
		if (xmlHTTP.readyState == 4 && xmlHTTP.status == 200) {
			obj.innerHTML = xmlHTTP.responseText;
		}
	}
	xmlHTTP.send(null);
}